Problem with compiled kernel 2.6.26fc+ unable to identify cdrom format

Rick Stevens ricks at
Mon Apr 13 17:37:05 UTC 2009

alok pandey wrote:
> HI,
> Still waiting for response, putting some more information for your better
> understanding.
> Exact error: in dmesg
> scsi 4:0:0:0: Direct-Access Dell Virtual Floppy 123 PQ: 0 ANSI: 0 CCS
> scsi 3:0:0:0: CD-ROM Dell Virtual CDROM 123 PQ: 0 ANSI: 0 CCS

If you see this, then the kernel knows about your CD-ROM device.  This
is not a kernel issue.

> sd 4:0:0:0: [sdc] Attached SCSI removable disk
>  "ISOFS: Unable to identify CD-ROM format"

That's pretty obvious.  The CD isn't burned correctly.

> Btw, I can mount ISO image successfully (i.e mount -t iso9660 -o lo
> /path/to/image /mount/point), So i am sure FS is well supported.

It is.  This is not a kernel or FS issue, it's a media problem.  The CD 
you're feeding your machine is NOT an ISO9660 CD.  The ISO image is
fine since you can mount it via loopback, but the CD itself is burned

> Attaching my config files as.
> LSPCI.txt :-> output of LSPCI command
> image-kernel-smpx86.conf:-> Kernel config paramater
> Bootfloppy-kernelXX.conf:->Boot image kernel config
> I have compiled the kernel to support cd-rom with my best linux knowledge,
> but unfortunately it's not working for me. I am quit sure that my kernel
> have all the required option enabled , it seems to me as kernel bug.
> You comment/suggestion is needed. Plz help.
> Thanks
> Alok Pandey
> On 4/10/09, alok pandey <alok.rhct at> wrote:
>> HI All,
>> Recently  I compiled a linux fedora kernel (2.6.27fc_x86_64bit) for stata
>> support. After successful compilation and installation with new kernel, :-
>>   --System is not able to mount cdrom.
>>  --Always generate error, "medium not found"
>> --dmesg have an  entry some thing like " unable to understand cdrom format"
>> I don't know what went wrong, but i cross checked my new kernel config and
>> my new kernel have following support:- (in respect of cdrom)
>>  --SCSI device drive support [*]
>> --iso9660 file system support [*]
>> --ata-ide device support [*]
>> I am attaching my kernel.conf file as attachment for better understanding.
>> let me know if some other information is need in order to understand my
>> issue.
>> Also,
>> I am highly confused in selection of modules as static or dynamic. It will
>> be great help if any one can suggest me the rule/law behind dynamic[M] and
>> static[*] selection of kernel modules.
>> *I just need to ask , what if i select all kernel modules as lodable
>> modules [M] instead of static modules [*] or vice versa !!
>> Thanks
>> -A
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- Rick Stevens, Systems Engineer                      ricks at -
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